Nitration of arylsulphonyl derivatives of aromatic amines



Patented Oct. 18, 1932 UNITED STATES PATENT oFFrcn DENIS HOUGHTON MOSBY, HENRY CHARLES OLPIN, AND GEORGE HOLLAND ELLIS, OF SPONDON, NEAR DERBY, ENGLAND, ASSIGNORS TO CELANESE CORPORATION OF AMERICA, A CORPORATION OF DELAWARE NITRATION OF ARYLSULPHONYL DERIVATIVES OF AROMATIC AMINE-S No Drawing. Application filed May 16, 1329, Serial No. 363,708, and in Great Britain June 18, 1928.

This invention relatesto the preparation of nitration products of arylsulphonyl derivatives of aromatic amines and to the production of nitrated aromatic amines from the said nitration products.

It is known that difficulties arise in the production of nitro derivatives of aromatic amines, and especially of those amines having one free para position and one free orthoposition, or two free ortho-positions to the amino group, for example aniline, o-anisidine, or p-toluidine, owing to the formation of mixtures of isomeric nitration products, or mixtures of lower with higher nitration products which mixtures are not readily separated into their components.

We have found that substantially pure nitration products (i. e. nitration products substantially free from isomers) may be obtained by nitrating arylsulphonyl derivatives. of aromatic amines by means of -75 per cent aqueous nitric acid and hydrolyzing the products. The nitration of arylsulphonyl deriva tives of aromatic amines with nitric acid of these concentrations leads to the formation, according to the conditions, of products which are monoor di-nitrated respectively in the amine nucleus. It is very remarkable that with such concentrations of nitric acid it is possible to obtain a substantially pure mononitration product, particularly in view of the fact that prior processes have adhered to the use of dilute nitric acid for this purpose; it is furthermore remarkable that by simply varying the conditions a substantially pure dinitration product may be obtained.

According therefore to the present invention the arylsulphonyl derivatives of aromatic amines are nitrated by means of 60 to per cent aqueous nitric acid. The greatest advantages of the present invention are obtained by using 60- 70 per cent nitric acid, and within this range the commercially available acid of about 65per cent concentration (specific gravity 1.4) may particularly be noted.

By subjecting the nitrated arylsulphonyl aromatic amines thus prepared to a process of hydrolysis the corresponding nitrated aromatic amines are obtained. The hydrolysis may be efi'ected in any convenient manner but preferably by the action of a concentrated strong mineral acid such as concentrated or moderately concentrated sulphuric acid. It is to be understood that the invention includes the nitration of arylsulphonyl derivatives of aromatic amines as described above whether or not the nitration products are subserivatives of the said amines may be used for example the benzene-sulphonyl derivatives.

In a similar manner may be nitrated the arylsulphonyl derivatives of aniline,o-toluidine, p-anisidine, oand p-phenetidine, and oand p-chloraniline, and the nitration products may be hydrolyzed with formation of the corresponding nitro amines. I

i It is immaterial, for the purposes of our invention, whether nitro groups-enter the arylsulpho residue as well as the aromatic amine residue in the course of the nitration process or do not soenter.

The products may be purified in any convenient manner. The dinitro-aromatic amines are preferably purified by taking advantage of their resistance to diazotization as compared with the ease of diazotization of any small quantities of lower nitration products which they may contain. Thus for example, if a crude dinitro-aromatic amineis treated with nitrous acid in presence of acid of such concentration that the dinitro com ,working up, for example, in the acid which has been used for the hydrolysis of the arylsulphonyl derivative, if necessary after suitably diluting. Thus hydrolysis of the arylsulphonyl-amino group may be first effected in moderately concentrated sulphuric acid solution at moderate temperatures and the solution diluted, for instance by pouring on to ice. The mixture thus obtained is then treated at an appropriate temperature, for

.example 510 (3., with sufficient nitrous acid to diazotize any impurities which on subsequent filtration are removed in the filtrate.

The invention is illustrated by the following examples but is not limited thereto.

Example 1 1 kilo of p-toluene sulphon-o-anisidide is stirred gradually into 3,600 grams of nitric acid 41 B. so that the temperature does not exceed G. hen all has been added the temperature is raised to 40 C. during one hour and kept at this point for a further four hours. The liquor is then diluted with water, and the precipitate filtered off, washed acid free, and dried.

The product of nitration is stirred into 3,600 grams of concentrated sulphuric acid (66 B.) the temperature not exceeding 35 (3.; 720 ccs. of water are then dripped in so that the temperature is kept at 50 C. This operation takes approximately 2 hours. The mixture is then poured on to ice and then 3,300 grams of soda ash are added to reduce the acidity of the liquor, and increase the yield. The precipitated 5-nitro-2-aminoanisole is filtered oil, well washed with cold water, a little dilute alkali, and again with water. Though a nitration tempera ture of C. has been specified in this example it is also possible to effect nitration at somewhat lower temperatures.

Example 2 1 kilo of p-toluene sulphon-o-anisidide is stirred into 3,600 grams of nitric acid 41 B, This operation should take approximately 1% hours so that the temperature does not exceed 40 C. The product is then maintained at 40 C. for 2 hours after which the temperature is raised to C. during 1 hour and stirring continued at this temperature for a further 6 hours. The nitration mixture is then allowed to stand overnight, when it is diluted with a large excess of water, filtered, washed, and the nitro body dried at 100 C.

The product from the nitration is stirred into 3,600 grams of 66 Be. sulphuric acid so that the temperature does not exceed 3035 0.; 720 ccs. of water are then dripped into the mixture so that the temperature is kept at 50 C. for approximately 2 hours. The mixture is then poured on toice, and stirred vigorously while grams of sodium nitrite dissolved in 450 cos. of water are stirred in. The whole is then filtered after stirring ten minutes. The dinitro-ortho-anisidine is washed with water, then with a little dilute alkali, and then with water, and finally dried at 100 C.

What we claim and desire to secure by Letters Patent is 7 1. A process which consists in nitrating arylsulphonyl derivatives of aromatic amines by ilneans of 60 to 75 per cent aqueous nitric aclc.

2. A process which consists in nitrating arylsulphonyl derivatives of aromatic amines byc lneans of 60 to 70 per cent aqueous nitric aci 3. A process which consists in nitrating arylsulphonyl derivatives of aromatic amines by means of 65 per cent aqueous nitric acid.

4. A process which consists in. nitrating arylsulphonyl derivatives of aromatic amines by means of 60 to per cent aqueous nitric acid and hydrolyzing the nitrated products.

5. A process which consists in nitrating arylsulphonyl derivatives of aromatic amines by means of 60 to 70 per cent aqueous nitric acid and hydrolyzing the nitrated products.

6. A process which consists in nitrating arylsulphonyl derivatives of aromatic amines by means of 65 per cent aqueous nitric acid and hydrolyzing the nitrated products.

7. A process which consists in nitrating arylsulphonyl derivatives of aromatic amines by means of 60 to 7 5 per cent aqueous nitric acid, hydrolyzing the dinitrated products, and purifying the dinitrated hydrolyzed product by treating with nitrous acid under conditions such that only lower nitration products are diazotized.

8. A process which consists in nitrating an arylsulphonyl-o-anisidine by means of 60 to 70 per cent aqueous nitric acid.

9. A process which consists in nitrating an arylsulphonyl-o-anisidine by means of 60 to 70 per cent aqueous nitric acid and hydrolyzing the nitrated products.

10. A process which consists in nitrating an arylsulphonyl-o-anisidine by means of 60 to 70 per cent aqueous nitric acid, hydrolyzing the dinitrated products, and purifying the dinitrated hydrolyzed product by treating with nitrous acid under conditions such that only lower nitration products are diazotized.

In testimony whereof we have hereunto subscribed our names.

DENIS HOUGHTON MOSBY. HENRY CHARLES OLPIN. GEORGE HOLLAND ELLIS. 

